This invention relates to a filtration device, and more particularly to a reef type filtration device for maintaining the quality of water in an aquarium.
There has been an increasing interest in the cultivation and raising of fish by hobbyists for their beauty and observation pleasure. In raising fish for their aesthetic value of viewing of the fish in a closed tank, the water must be recirculated and purified not only to keep the fish alive, but to provide a clear visually attractive medium in which to view the fish. In closed or semi-open systems, it is necessary to filter the water both for physical filtration to remove solid matter from the water, as well as to treat the water to remove dissolved chemical contaminants from the water. The waste products of fish ultimately generate ammonia which is highly toxic to fish and other aquatic animals. In a closed or semi-open system, it is therefore necessary to provide means for removing ammonia and other nitrogenous wastes from the water. Generally, this involves cultivating aerobic bacteria colonies which utilize nitrogenous waste in their nutritional cycle and convert these wastes to less toxic compounds and exposing the bacteria to the aquarium water to remove the ammonia. While creation of these bacterial colonies has been efficiently accomplished for some fish tank filtration systems, the cost of most of these systems and the filter media used still is a significant cost for the home aquarium hobbyist.
For healthy growth of aquatic aerobic bacteria colonies a number of conditions must be met. First, an adequate oxygen supply must be present in the water since these bacteria are aerobic and thus dependent upon oxygen. Second, the flow rate of water must be maintained and controlled since stagnation of water in the filter medium will result in oxygen depletion and killing of the bacteria. Not only will the aerobic bacteria starve, but anaerobic bacteria will be encouraged, which are hazardous to the health of the fish. Thirdly, another problem faced in any filtration device is that of channeling of the water through the filter media, which again limits the effectiveness of the filter and tends to greatly decrease the filter surface area and the growth of the aerobic bacteria needed. Another factor is the need for a large surface area media on which the aerobic bacteria can grow. Generally speaking, the greater the surface area exposed to adequate flow rates and levels of oxygen, the greater the number of aerobic bacteria colonies that can be maintained in a given volume. This concept can be carried to the extreme of using the large surface area of sand or some such finely divided media for the growth of the bacteria, but then flow becomes very important and extremely difficult to maintain in a uniform and efficient fashion. Accordingly, most small aquariums have developed filtration systems using a plastic material media having large numbers of small rods or other surface forming elements upon which the aerobic bacteria can grow, and through which sufficient flow of water and oxygen can be provided.
Another problem that has affected the hobbyist industry, even in the improved filtration devices using a high surface area plastic media, is that of cleaning the device. Unfortunately, when the filter media are back-flushed or otherwise cleaned, most of the bacteria colonies are destroyed, along with the cleaning of the filter. It thus takes a significant amount of time for the colonies to be regrown before they can continue to do the necessary purifying and filtering of the water from the aquarium. With larger, more expensive filter units common in the hobby industry, the only recourse for the home hobbyist is to periodically clean and then to suffer the consequences for the next few days.